Methods and apparatus to facilitate PDCCH monitoring in carrier aggregation for lower power consumption

ABSTRACT

The present disclosure relates to technique for facilitating PDCCH monitoring in carrier aggregation for lower power consumption. A UE monitors a physical downlink control channel (PDCCH) on a secondary cell (SCell). The UE stops the PDCCH monitoring on the SCell in response to a monitoring-stoppage event. Then, the UE resumes the PDCCH monitoring on the SCell in response to a monitoring-resumption event. The SCell may remain active during a period between the stopping of the PDCCH monitoring and the resuming of the PDCCH monitoring.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Patent ProvisionalApplication Ser. No. 62/825,738, entitled “METHODS AND APPARATUS TOFACILITATE PDCCH MONITORING IN CARRIER AGGREGATION FOR LOWER POWERCONSUMPTION” and filed on Mar. 28, 2019, which is expressly incorporatedby reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure relates generally to communication systems, andmore particularly, to wireless communication including PDCCH monitoring.

Introduction

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. 5G NR includes services associated with enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), and ultrareliable low latency communications (URLLC). Some aspects of 5G NR maybe based on the 4G Long Term Evolution (LTE) standard. There exists aneed for further improvements in 5G NR technology. These improvementsmay also be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

When a user equipment (UE) is configured with carrier aggregation (CA),some secondary cells (SCells) may be configured with their own physicaldownlink control channel (PDCCH). In some such examples, downlinkcontrol information (DCI) for downlink assignments and/or uplink grantson those SCells may be sent in their own PDCCH. These types of SCellsmay be referred to as “self-scheduling SCells.”

In some examples, a UE may monitor PDCCH on a self-scheduling SCelluntil the self-scheduling SCell is deactivated. Since reactivating adeactivated SCell may incur delays, the network may keep an SCell activeuntil the network determines that there is no more data to communicatein the near future. However, since it may be power intensive for a UE tomonitor PDCCH continuously, it may be inefficient for the UE to monitorPDCCH while there is no or little traffic, for example, between datatraffic bursts.

Techniques disclosed herein facilitate monitoring PDCCH when needed(e.g., when a traffic load is high). For example, disclosed techniquesenable keeping a self-scheduling SCell active, but also enable a UE tostop monitoring PDCCH when there is a period of inactivity in traffic.By keeping the self-scheduling SCell active, techniques disclosed hereinmay enable reducing UE power consumption and may also enable avoidinglatency incurred by re-activating the SCell.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are disclosed. An example apparatus for wirelesscommunication at a user equipment (UE) monitors a physical downlinkcontrol channel (PDCCH) on a secondary cell (SCell). The exampleapparatus stops the PDCCH monitoring on the SCell in response to amonitoring-stoppage event. The example apparatus resumes the PDCCHmonitoring on the SCell in response to a monitoring-resumption event. Insome examples, the SCell may remain active during a period between thestopping of the PDCCH monitoring and the resuming of the PDCCHmonitoring.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a first5G/NR frame, DL channels within a 5G/NR subframe, a second 5G/NR frame,and UL channels within a 5G/NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 is an example communication flow between a UE, a base station,and an SCell, in accordance with the teachings disclosed herein.

FIG. 5 is a flowchart of wireless communication, in accordance with theteachings disclosed herein.

FIGS. 6A to 6E are flowcharts of wireless communication, includingtriggering of monitoring-stoppage events, in accordance with theteachings disclosed herein.

FIGS. 7A to 7F are flowcharts of wireless communication, includingtriggering of monitoring-resumption events, in accordance with theteachings disclosed herein.

FIG. 8 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an example apparatus.

FIG. 9 is a diagram illustrating an example of a hardware implementationfor an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

As used herein, the term computer-readable medium is expressly definedto include any type of computer readable storage device and/or storagedisk and to exclude propagating signals and to exclude transmissionmedia. As used herein, “computer-readable medium,” “machine-readablemedium,” “computer-readable memory,” and “machine-readable memory” maybe used interchangeably.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, an Evolved Packet Core (EPC) 160, and anothercore network 190 (e.g., a 5G Core (5GC)). The base stations 102 mayinclude macrocells (high power cellular base station) and/or small cells(low power cellular base station). The macrocells include base stations.The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to asEvolved Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (E-UTRAN)) may interface with the EPC 160 throughfirst backhaul links 132 (e.g., S1 interface). The base stations 102configured for 5G NR (collectively referred to as Next Generation RAN(NG-RAN)) may interface with core network 190 through second backhaullinks 184. In addition to other functions, the base stations 102 mayperform one or more of the following functions: transfer of user data,radio channel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over third backhaul links 134 (e.g., X2interface). The third backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, FlashLinQ, WiMedia,Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include and/or be referred to as an eNB, gNodeB(gNB), or another type of base station. Some base stations, such as gNB180 may operate in a traditional sub 6 GHz spectrum, in millimeter wave(mmW) frequencies, and/or near mmW frequencies in communication with theUE 104. When the gNB 180 operates in mmW or near mmW frequencies, thegNB 180 may be referred to as an mmW base station. Extremely highfrequency (EHF) is part of the RF in the electromagnetic spectrum. EHFhas a range of 30 GHz to 300 GHz and a wavelength between 1 millimeterand 10 millimeters. Radio waves in the band may be referred to as amillimeter wave. Near mmW may extend down to a frequency of 3 GHz with awavelength of 100 millimeters. The super high frequency (SHF) bandextends between 3 GHz and 30 GHz, also referred to as centimeter wave.Communications using the mmW/near mmW radio frequency band (e.g., 3GHz-300 GHz) has extremely high path loss and a short range. The mmWbase station 180 may utilize beamforming 182 with the UE 104 tocompensate for the extremely high path loss and short range. The basestation 180 and the UE 104 may each include a plurality of antennas,such as antenna elements, antenna panels, and/or antenna arrays tofacilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMES 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The core network 190 may include a Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides QoS flow andsession management. All user Internet protocol (IP) packets aretransferred through the UPF 195. The UPF 195 provides UE IP addressallocation as well as other functions. The UPF 195 is connected to theIP Services 197. The IP Services 197 may include the Internet, anintranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service,and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B,eNB, an access point, a base transceiver station, a radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), a transmit reception point (TRP), or someother suitable terminology. The base station 102 provides an accesspoint to the EPC 160 or core network 190 for a UE 104. Examples of UEs104 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heartmonitor, etc.). The UE 104 may also be referred to as a station, amobile station, a subscriber station, a mobile unit, a subscriber unit,a wireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology.

Referring again to FIG. 1, in certain aspects, the UE 104 may beconfigured to manage one or more aspects of wireless communicationincluding PDCCH monitoring in carrier aggregation for lower powerconsumption. For example, the UE 104 of FIG. 1 includes a PDCCHmonitoring component 198 configured to monitor a physical downlinkcontrol channel (PDCCH) on a secondary cell (SCell). The PDCCHmonitoring component 198 may also be configured to stop the PDCCHmonitoring on the SCell in response to a monitoring-stoppage event. Insome examples, the event may include the reception of a signal.Additionally, the PDCCH monitoring component 198 may be configured toresume the PDCCH monitoring on the SCell in response to amonitoring-resumption event. In some examples, the event may includereception of a signal. In some examples, the SCell remains active duringa period between the stopping of the PDCCH monitoring and the resumingof the PDCCH monitoring.

Although the following description provides examples related to 5G/NR,the concepts described herein may be applicable to other similar areas,such as LTE, LTE-A, CDMA, GSM, and/or other wireless technologies, inwhich a UE monitoring PDCCH on a self-serving SCell may incur powerconsumption costs and/or in which deactivating and activating of PDCCHmonitoring on a self-scheduling SCell may incur long latency costs.

Furthermore, although the following description may be focused onmonitoring PDCCH on self-scheduling SCells, the concepts describedherein may additionally or alternatively be applicable to othercomponent carriers in a carrier aggregation.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G/NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G/NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G/NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G/NR subframe. The 5G/NR frame structure may be FDDin which for a particular set of subcarriers (carrier system bandwidth),subframes within the set of subcarriers are dedicated for either DL orUL, or may be TDD in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G/NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and X isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G/NR frame structure that is TDD.

Other wireless communication technologies may have a different framestructure and/or different channels. A frame (10 ms) may be divided into10 equally sized subframes (1 ms). Each subframe may include one or moretime slots. Subframes may also include mini-slots, which may include 7,4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on theslot configuration. For slot configuration 0, each slot may include 14symbols, and for slot configuration 1, each slot may include 7 symbols.The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Thesymbols on UL may be CP-OFDM symbols (for high throughput scenarios) ordiscrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (alsoreferred to as single carrier frequency-division multiple access(SC-FDMA) symbols) (for power limited scenarios; limited to a singlestream transmission). The number of slots within a subframe is based onthe slot configuration and the numerology. For slot configuration 0,different numerologies μ0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots,respectively, per subframe. For slot configuration 1, differentnumerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, persubframe. Accordingly, for slot configuration 0 and numerology μ, thereare 14 symbols/slot and 2^(μ) slots/subframe. The subcarrier spacing andsymbol length/duration are a function of the numerology. The subcarrierspacing may be equal to 2^(μ)*15 kHz, where μ is the numerology 0 to 5.As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and thenumerology μ=5 has a subcarrier spacing of 480 kHz. The symbollength/duration is inversely related to the subcarrier spacing. FIGS.2A-2D provide an example of slot configuration 0 with 14 symbols perslot and numerology μ=2 with 4 slots per subframe. The slot duration is0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration isapproximately 16.67 μs.

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as R_(x) for one particular configuration, where 100x is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A primary synchronization signal (PSS) may be within symbol2 of particular subframes of a frame. The PSS is used by a UE 104 todetermine subframe/symbol timing and a physical layer identity. Asecondary synchronization signal (SSS) may be within symbol 4 ofparticular subframes of a frame. The SSS is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DM-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSS and SSS to form a synchronization signal (SS)/PBCH block. TheMIB provides a number of RBs in the system bandwidth and a system framenumber (SFN). The physical downlink shared channel (PDSCH) carries userdata, broadcast system information not transmitted through the PBCH suchas system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. The UE may transmit sounding referencesignals (SRS). The SRS may be transmitted in the last symbol of asubframe. The SRS may have a comb structure, and a UE may transmit SRSon one of the combs. The SRS may be used by a base station for channelquality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. ThePUSCH carries data, and may additionally be used to carry a bufferstatus report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with the PDCCH monitoring component 198 of FIG. 1.

When a user equipment (UE) is configured with carrier aggregation (CA),some secondary cells (SCells) may be configured with their own physicaldownlink control channel (PDCCH). In some such examples, downlinkcontrol information (DCI) for downlink assignments and/or uplink grantson those SCells may be sent in their own PDCCH. These types of SCellsmay be referred to as “self-scheduling SCells.”

In some examples, a UE may monitor PDCCH on a self-scheduling SCelluntil the self-scheduling SCell is deactivated. In some examples, anSCell may be de-activated by, for example, signaling (e.g., an SCellde-activation MAC-CE) or a timer (e.g., expiration of an SCellde-activation timer). Since reactivating a deactivated SCell may incurdelays (sometimes significant delays), the network may keep an SCellactive until the network determines that there is no more data tocommunicate in the near future. However, since it may be power intensivefor a UE to monitor PDCCH continuously, it may be inefficient for the UEto monitor PDCCH while there is no or little traffic, for example,between data traffic bursts. Furthermore, in some examples, deactivatingand reactivating of the SCell may prompt radio resource control (RRC)reconfiguration of the PDCCH configuration (e.g., by re-designing asearch space, configuring a control resource set (CORESET), etc.), whichmay introduce additional latency and/or that may reduce any powersavings that may be experienced by deactivating the SCell.

Techniques disclosed herein facilitate monitoring PDCCH when needed(e.g., when a traffic load is high). For example, disclosed techniquesenable keeping a self-scheduling SCell active, but also enable a UE tostop monitoring PDCCH on the self-scheduling SCell when there is aperiod of inactivity in traffic. By keeping the self-scheduling SCellactive, techniques disclosed herein may enable reducing UE powerconsumption and may also enable avoiding latency incurred byre-activating the SCell. Thus, it may be appreciated that techniquesdisclosed herein provide a low-latency technique for a UE to stop andrestart monitoring PDCCH on a self-scheduling SCell.

FIG. 4 illustrates an example of wireless communication 400 between abase station 402, a UE 404, and an SCell 406, as presented herein. Inthe illustrated example, the SCell 406 is a self-scheduling SCell. Oneor more aspects of the base station 402 may be implemented by the basestation 102 of FIG. 1 and/or the base station 310 of FIG. 3. One or moreaspects of the UE 404 may be implemented by the UE 104 of FIG. 1 and/orthe UE 350 of FIG. 3. In the illustrated example of FIG. 4 (and asdisclosed herein), the UE 404 may stop PDCCH monitoring on the SCell 406when overall traffic load is low, and may resume PDCCH monitoring on theSCell 406 when traffic resumes.

While the wireless communication 400 includes one base station 402 andone SCell 406 in communication with the UE 404, in additional oralternative examples, the UE 404 may be in communication with anysuitable quantity of base stations and/or SCells. For example, the UE404 may be in communication with zero, one, two, or more base stationsand/or the UE 404 may be in communication with zero, one, two, or moreSCells (sometimes referred to as a set of SCells). Furthermore, whilethe wireless communication 400 indicates that the UE 404 stops andresumes PDCCH monitoring on the SCell 406, in additional or alternativeexamples, the UE 404 may stop PDCCH monitoring on a first SCell (e.g.,the SCell 406) based on the occurrence of a monitoring-stoppage event.In some examples, the event may include reception of signaling from abase station. The UE may start (or resume) PDCCH monitoring on a secondSCell (e.g., the SCell 406 and/or one or more additional SCells) basedon the occurrence of a monitoring-resumption event. In some examples,the even may include reception of signaling from a base station.

The UE 404 may receive a communication 410 from the base station 402configuring the UE 404 with the SCell 406 and activating the SCell 406.In some examples, the base station 402 may add the SCell 406 to aprimary cell (PCell) and/or to a set of SCells via an RRC connectionreconfiguration procedure. The UE 404 may then begin monitoring PDCCH412 on the SCell 406. The UE 404 may detect, at 414, low overall trafficon the SCell 406, and stop monitoring PDCCH on the SCell 406, at 416. Insome examples, and as described below, the UE 404 may detect the lowoverall traffic based on, for example, a timer, network signaling,and/or an occurrence of a predefined event. The UE 404 may then detect,at 418, that traffic resumed, and resume monitoring PDCCH on the SCell406, at 420. In some examples, and as described below, the UE 404 maydetect that traffic resumed based on, for example, network signalingand/or an occurrence of a predefined event.

In some examples, the UE 404 may stop PDCCH monitoring on the SCell 406based on a timer. For example, the UE 404 may include an SCellinactivity timer (SIT) that is started or restarted by transmission orreception of data on the SCell 406. In some such examples, the UE 404may stop monitoring PDCCH on the SCell 406 in response to the SCellinactivity timer expiring. In some examples, the UE 404 may retain thecurrent (or active) bandwidth part (BWP) associated with the SCell, butmay stop monitoring PDCCH on that SCell. In some examples, the UE 404may switch from an active BWP to a different BWP that does not containPDCCH. In some such examples, the UE 404 may autonomously switch fromthe active BWP to the different BWP. For example, the UE 404 may switchform the active BWP to the different BWP without receiving signaling(e.g., from the base station 402 and/or the SCell 406).

In some examples, the UE 404 may stop PDCCH monitoring on the SCell 406based on a signal received from the network. For example, the UE 404 mayreceive downlink control information (DCI) from the base station 402. Insome examples, the DCI received from the base station 402 may be similarto DCI used for de-activating a type-2 uplink configured grant and/ormay be similar to DCI used for de-activating type-2 downlinksemi-persistent scheduling (SPS). In some examples, the DCI receivedfrom the base station 402 may be scheduling DCI that may cause the UE404 to switch from an active BWP to a different BWP (e.g., perform a BWPswitch) that does not contain PDCCH.

In some examples, the signal (or signaling) received from the networkmay be a medium access control-control element (MAC-CE). In some suchexamples, the MAC-CE may indicate a particular SCell and/or a set ofSCells f that the UE 404 is to stop PDCCH monitoring.

In some examples, the occurrence of a predefined event may trigger theUE 404 to stop PDCCH monitoring on the SCell 406. For example, the UE404 may be configured with connected mode discontinuous reception(C-DRX). In some such examples, the base station 402 may configure theUE 404 with C-DRX parameters. For example, the C-DRX parameters mayinclude a set of SCells for which the UE is to perform PDCCH monitoring.In some such examples, the C-DRX parameters may additionally oralternatively identify a subset of SCells of the set of SCells for whichthe UE 404 is to stop PDCCH monitoring at the start of a C-DRX ONduration. The subset of SCells may include any suitable quantity ofSCells of the set of SCells including, for example, zero SCells of theset of SCells to all of the SCells of the set of SCells. In someexamples, the subset of SCells may include a quantity of SCells and/ormay include identifiers for particular SCells (e.g., of the set ofSCells).

Thus, as described above, in some examples, the UE 404 may stop PDCCHmonitoring on the SCell 406 while keeping the SCell active (e.g.,without de-activating the SCell 406).

In some examples, and as described above at 420, the UE 404 may resumePDCCH monitoring on the SCell. For example, the UE 404 may resume PDCCHmonitoring on a first SCell (e.g., the SCell 406). In other examples,the UE 404 may additionally or alternatively resume (or start) PDCCHmonitoring on a second SCell different than the first SCell, may resume(or start) PDCCH monitoring on a set of SCells including the firstSCell, and/or may resume (or start) PDCCH monitoring on a set of SCellsthat does not include the first SCell. The UE 404 may resume (or start)PDCCH monitoring on the SCell based on network signaling and/or anoccurrence of a predefined event.

In some examples, the UE 404 may resume PDCCH monitoring on the SCell406 (at 420) based on network signaling received from the network. Forexample, the UE 404 may receive DCI from the base station 402. In someexamples, the UE 404 may be capable of cross-carrier signaling thatenables the UE 404 to connect to different cells to receive PDCCH ondifferent carriers. In some such examples, the DCI received from thebase station 402 may be received from a fallback cell for which the UE404 is still performing PDCCH monitoring. For example, after the UE 404stops PDCCH monitoring on a first SCell (e.g., at 416), the UE 404 mayreceive DCI for the first SCell from the fallback cell. In someexamples, the fallback cell may be a designated (or pre-configured)SCell that the UE 404 is monitoring. In some examples, the fallback cellmay be a primary cell (PCell).

In some examples, the DCI received from base station 402 may be similarto DCI used for activating a type-2 uplink configured grant and/or maybe similar to DCI used for activating type-2 downlink semi-persistentscheduling (SPS). In some examples, the DCI received from the basestation 402 may be scheduling DCI that may cause the UE 404 to switchfrom an active BWP to a different BWP (e.g., perform a BWP switch) thatcontains PDCCH.

In some examples, the signal received from the network may be a mediumaccess control (MAC) control element (CE). In some such examples, theMAC-CE may indicate a particular SCell and/or a set of SCells for whichthe UE 404 is to resume (or start) PDCCH monitoring.

In some examples, the signal received from the network may be a wakeupsignal (WUS). For example, the UE 404 may be configured with connectedmode discontinuous reception (C-DRX) and the base station 402 mayconfigure the UE 404 with C-DRX parameters including a set of SCells. Insome such examples, the base station 402 may transmit a WUS to the UE404 (e.g., at the start of a C-DRX ON duration) indicating a subset ofSCells of the set of SCells for which the UE 404 is to resume (or start)PDCCH monitoring.

In some examples, the occurrence of a predefined event may trigger theUE 404 to resume PDCCH monitoring on an SCell. In some such examples,the predefined event may be associated with C-DRX states. For example,when a C-DRX inactivity timer is started or restarted (e.g., uponreceipt of PDCCH for transmission of data or receipt of data), the UE404 may resume (or start) PDCCH monitoring on a subset of SCells of theset of SCells. In some such examples, the base station 402 may configurethe UE 404 with C-DRX parameters including the subset of SCells of theset of SCells to monitor during respective C-DRX states.

In some examples, the subset of SCells (e.g., of the WUS and/or theC-DRX parameters) may include any suitable quantity of SCells of the setof SCells including, for example, zero SCells of the set of SCells toall of the SCells of the set of SCells. In some examples, the subset ofSCells may include a quantity of SCells and/or may include identifiersfor particular SCells (e.g., of the set of SCells).

In some examples, the UE 404 may resume (or start) PDCCH monitoring onan SCell based on DCI and a linkage (e.g., an implied linkage) between asearch space of a PCell and a set of SCells. For example, the networkmay designate a search space associated with a PCell and also link a setof SCells to the designated search space. In some such examples,scheduling DCI received in the designated search space may cause the UE404 to resume PDCCH monitoring on the linked set of SCells.

As an illustrative example, consider an example in which the UE receivesDCI in a first search space on a PCell on PDCCH and that the firstsearch space is linked to a first SCell. It may be appreciated that theUE has at least one search space in a PDCCH. In some such examples, ifthe UE receives scheduling DCI in the first search space on the PCell,then the UE may resume monitoring PDCCH on the first SCell. In someexamples, if the UE has previously stopped monitoring PDCCH on the firstSCell (e.g., in response to a monitoring-stoppage event), then the UEmay continue not monitoring PDCCH on the first SCell as long as the UEdoes not receive DCI in the first search space on the PCell. In someexamples, the event may be based on an indication or signal receivedfrom the base station. In some examples, the linkage between the searchspace and the SCell may be a many-to-one linkage. For example, a set ofSCells may be linked to a same search space on a PCell. The set ofSCells may include any appropriate quantity of SCells, including, forexample, one SCell, two SCells, etc.

Thus, as described above, in some examples, the UE 404 may resume PDCCHmonitoring on an SCell after stopping the PDCCH monitoring on the SCell.In some such examples, because the SCell is still active when the UE 404stops the PDCCH monitoring on the SCell, the UE 404 may resume the PDCCHmonitoring relatively quickly (e.g., as compared to performing an RRCconnection reconfiguration procedure to activate the SCell). Thus, thetechniques disclosed herein facilitate low-latency (e.g., relativelyfast) stopping and resuming of PDCCH monitoring of one or more SCells.

FIG. 5 is a flowchart 500 of a method of wireless communication. Themethod may be performed by a UE or a component of a UE (e.g., the UE 104of FIG. 1, the UE 350 of FIG. 3, the UE 404 of FIG. 4, the apparatus802/802′ of FIGS. 8 and 9, respectively; the processing system 914,which may include the memory 360 of FIG. 3 and which may be the entireUE 350, or a component of the UE 350, such as the TX processor 368, theRX processor 356, and/or the controller/processor 359). The method mayenable a UE or other wireless device to reduce power consumption duringPDCCH monitoring and/or perform low-latency stopping and resuming ofPDDCH monitoring. Optional aspects are illustrated with a dashed line.

At 502, the UE monitors a PDCCH on a SCell, as described in connectionwith, for example, monitoring PDCCH 412 on the SCell 406 of FIG. 4. Forexample, a traffic monitoring component 806 may facilitate themonitoring of PDCCH on an SCell. The SCell may be an active SCellassociated with a base station and in communication with the UE.

As illustrated at 504, the UE may determine an occurrence of amonitoring-stoppage event. For example, the traffic monitoring component806, the timer component 808, the DCI handling component 810, the MAC-CEhandling component 814, and/or the C-DRX handling component 816 mayfacilitate the determination that the monitoring-stoppage signaling hasoccurred. As described above in connection with the wirelesscommunication 400 of FIG. 4, and as described below in connection withthe flowcharts of FIGS. 6A to 6E, the monitoring-stoppage event mayinclude, for example, expiration of a timer (e.g., an SCell inactivitytimer), reception of signaling from a base station (e.g., a received DCIand/or a received MAC-CE), and/or the occurrence of a predefined event(e.g., the start of a C-DRX ON duration).

As illustrated at 506, the UE stops the PDCCH monitoring on the SCell inresponse to the monitoring-stoppage event, as described in connectionwith, for example, 416 of FIG. 4. For example, the stop monitoringcomponent 818 may facilitate the stopping of the PDCCH monitoring on theSCell. In some examples, the UE stops the PDCCH monitoring on the SCellwhile the SCell remains active. As illustrated at 416 in FIG. 4, the UEmay stop the PDCCH monitoring on the SCell. By stopping the performingof the PDCCH monitoring on the SCell if the monitoring-stoppage eventoccurs, the UE may conserve power by not continuously monitoring PDCCHon the SCell while there is no or limited traffic on the SCell.

As illustrated at 508, the UE may determine that a monitoring-resumptionevent has occurred. For example, the traffic monitoring component 806,the timer component 808, the DCI handling component 810, the MAC-CEhandling component 814, and/or the C-DRX handling component 816 maydetermine the occurrence of the PDCCH monitoring-resumption. Asdescribed above in connection with the wireless communication 400 ofFIG. 4, and as described below in connection with the flowcharts ofFIGS. 7A to 7F, the monitoring-resumption event may include networksignaling (e.g., a received DCI, a received wakeup signal, a receivedMAC-CE, and/or a received scheduling DCI) and/or the occurrence of apredefined event (e.g., the starting or restarting of a C-DRX inactivitytimer).

As illustrated at 510, the UE resumes the PDCCH monitoring on the SCellin response to the monitoring-resumption event, as described inconnection with, for example, 420 of FIG. 4. For example, the resumemonitoring component 820 may facilitate the resuming of the PDCCHmonitoring on the SCell. In some examples, the UE resumes the PDCCHmonitoring on the SCell while the SCell remains active. In some suchexamples, the UE may not incur latency costs by waiting to re-active theSCell before resuming PDCCH monitoring on the SCell. As illustrated at420 in FIG. 4, the UE may resume the PDCCH monitoring on the SCell.

In some examples, the SCell remains active during a period betweenstopping the PDCCH monitoring and resuming the PDCCH monitoring. Forexample, the UE may stop the PDCCH monitoring on the SCell at a firsttime, and the UE may resume the PDCCH monitoring on the SCell at asecond time. In some such examples, the SCell may remain active duringthe time between the first time and the second time.

By keeping the SCell active between the first time and the second time,the UE may be able to reduce latency associated with transitioning fromnot performing PDCCH monitoring on the SCell to performing PDCCHmonitoring on the SCell. Furthermore, by stopping the PDCCH monitoringon the SCell during, for example, periods of relatively low data trafficloads, the UE may be able to conserve power.

FIGS. 6A to 6E illustrate example techniques for determining amonitoring-stoppage event has occurred, as disclosed herein. Forexample, one or more of the example techniques of FIGS. 6A to 6E may beused to determine the occurrence of the monitoring-stoppage event at 504and to stop the PDCCH monitoring at 506 of FIG. 5. The exampletechniques may enable a UE or other wireless device to reduce powerconsumption during PDCCH monitoring by stopping the performing of PDCCHmonitoring on the SCell. Optional aspects are illustrated with a dashedline.

FIG. 6A is a flowchart 600 of an example method of determining anoccurrence of the monitoring-stoppage event based on a minimum trafficthreshold. For example, at 602, the UE may determine whether a datatraffic load on the SCell satisfies a minimum traffic threshold (e.g.,the data traffic load on the SCell is greater than the minimum trafficthreshold), as described in connection with, for example, 414 of FIG. 4.For example, the traffic monitoring component 806 may facilitatedetermining whether the data traffic load on the SCell satisfies theminimum traffic threshold. At 604, the UE stops PDCCH monitoring on theSCell when the data traffic load on the SCell fails to satisfy theminimum traffic threshold, as described in connection with, for example,414 of FIG. 4. For example, traffic monitoring component 806 maydetermine the occurrence of the monitoring-stoppage event and maytrigger the stopping of the PDCCH monitoring. For example, the minimumtraffic threshold may correspond to a quantity of traffic indicative ofdata transfer. In some such examples, when the data traffic load on theSCell fails to satisfy the minimum traffic threshold (e.g., the datatraffic load on the SCell is less than the minimum traffic threshold),the UE may operate as if little or no traffic is being transmitted orreceived on the SCell and, thus, may initiate the stopping the PDCCHmonitoring on the SCell.

Although not shown in FIG. 6A, when the data traffic load on the SCellsatisfies the minimum traffic threshold (e.g., the data traffic load onthe SCell is greater than or equal to the minimum traffic threshold),the UE continues PDCCH monitoring on the SCell.

FIG. 6B is a flowchart 610 of an example method of determining themonitoring-stoppage event based on a timer. For example, at 612, the UEmay start or restart a timer (e.g., the SCell inactivity timer) inresponse to transmission of a subsequent (or new) physical uplink sharedchannel (PUSCH) on the SCell or reception of a subsequent (or new)physical downlink shared channel (PDSCH) on the SCell. For example, thetimer component 808 may facilitate the starting or restarting of atimer. In some examples, the UE may initiate a different SCellinactivity timer for each active SCell in communication with the UE. At614, the UE may stop the PDCCH monitoring on the SCell when an SCellinactivity timer expires. For example, the timer component 808 maydetermine the occurrence of the monitoring-stoppage event when the SCellinactivity timer expires and may trigger the stopping of the PDCCHmonitoring. In some such examples, the UE may determine, based on theSCell inactivity timer expiring, that the traffic load on thecorresponding SCell is relatively low and, thus, may initiate thestopping of PDCCH monitoring on the corresponding SCell.

In some examples, at 616, the UE may maintain an active bandwidth part(BWP), but may stop PDCCH monitoring on the SCell. For example, thestop-monitoring component 818 may be configured to maintain an activeBWP while stopping PDCCH monitoring on the SCell. For example, the UEmay be configured with one or more bandwidth parts, but at any one time,the UE may operate using one BWP (sometimes referred to as an “activebandwidth part”). In some such examples, the UE may maintain (or retain)the active BWP while stopping PDCCH monitoring on the SCell.

In some examples, at 618, the UE may switch to a different BWP that doesnot include a PDCCH. For example, the stop monitoring component 818 mayperform the switch to the different BWP that does not include PDCCH. Forexample, the UE may switch (e.g., autonomously switch) from the activeBWP to a different BWP (e.g., by performing a BWP switch) that does notinclude a PDCCH.

FIG. 6C is a flowchart 620 of an example method of determining anoccurrence of the monitoring-stoppage event based on network signaling.For example, at 622, the UE receives DCI from a base station. Forexample, the DCI handling component 810 may receive the DCI. In someexamples, the base station may be associated with the SCell. In someexamples, the received DCI may be similar to the DCI used to de-activatetype-2 uplink configured grants and/or may be similar to the DCI used tode-activate type-2 downlink semi-persistent scheduling (SPS). In someexamples, the received DCI may be a scheduling DCI. At 624, the UE stopsthe PDCCH monitoring on the SCell in response to the received DCI. Forexample, the DCI handling component 810 may determine the occurrence ofthe monitoring-stoppage event and may trigger the stopping of the PDCCHmonitoring. At 626, the UE may switch from an active BWP to a differentBWP that does not include a PDCCH based on instructions in the receivedDCI. For example, the stop monitoring component 818 may perform theswitch from the active BWP to a different BWP. For example, thescheduling DCI may include instructions that cause the UE to perform aBWP switch to switch from the active BWP to the different BWP. In someexamples, the UE may perform the BWP switch based on a change in trafficload of the UE.

FIG. 6D is a flowchart 630 of another example method of determining anoccurrence of the monitoring-stoppage signaling based on networksignaling. For example, at 632, the UE receives a MAC-CE from a basestation. For example, the MAC-CE handling component 814 may facilitatethe receiving of the MAC-CE. In some examples, the base station may beassociated with the SCell. In some examples, the received MAC-CE mayindicate to the UE to stop PDCCH monitoring on one or more SCells. At634, the UE may determine the occurrence of the monitoring-stoppagebased on reception of the MAC-CE, and may stop the PDCCH monitoringSCell in response to receiving the MAC-CE. For example, the MAC-CEhandling component 814 may be configured to determine the occurrence ofthe monitoring-stoppage and to stop the PDCCH monitoring on the SCell inresponse to the received MAC-CE. For example, the UE may stop PDCCHmonitoring on the one or more SCells indicated in the MAC-CE.

FIG. 6E is a flowchart 640 of an example method of triggering themonitoring-stoppage event based on a predefined event. For example, at642, the UE may detect an occurrence of a predefined event. For example,the C-DRX handling component 816 may detect the occurrence of thepredefined event. In some examples, the UE may be configured withconnected mode discontinuous reception (C-DRX). In some such examples,at 644, the predefined event may be the start of a C-DRX ON duration.For example, the C-DRX handling component 816 may detect the start ofthe C-DRX ON duration. At 646, the UE may determine the occurrence ofthe monitoring-stoppage signaling based on the occurrence of thepredefined event. For example, the C-DRX handling component 816 maydetermine the occurrence of the monitoring-stoppage event and maytrigger the stopping of the PDCCH monitoring on the SCell. For example,the UE may stop PDCCH monitoring on one or more SCells at the start ofC-DRX ON duration.

FIGS. 7A to 7F illustrate example techniques for determining anoccurrence of a monitoring-resumption event, as disclosed herein. Forexample, one or more of the example techniques of FIGS. 7A to 7F may beused to implement the determine the occurrence of themonitoring-resumption event at 508 and to resume PDCCH monitoring at 510of FIG. 5. The example techniques may enable a UE or other wirelessdevice to reduce latency when transitions from not performing PDCCHmonitoring to performing PDCCH monitoring. Optional aspects areillustrated with a dashed line.

FIG. 7A is a flowchart 700 of an example method of determining anoccurrence of the monitoring-resumption event based on a trafficthreshold. For example, at 702, the UE may determine whether a datatraffic load on the SCell is greater than a traffic threshold. Forexample, the traffic monitoring component 806 may facilitate thedetermining of whether the data traffic load on the SCell is greaterthan the traffic threshold. At 704, the UE may resume PDCCH monitoringon the SCell when the data traffic load on the SCell is greater than thetraffic threshold. For example, the traffic monitoring component 806 maydetermine an occurrence of the monitoring-resumption event and maytrigger resumption of the PDCCH monitoring on the SCell. For example,the traffic threshold may correspond to a quantity of traffic indicativeof data transfer. In some such examples, when the data traffic load onthe SCell is greater than the traffic threshold, the UE may operate asif traffic has resumed on the SCell and, thus, may resuming the PDCCHmonitoring on the SCell.

Although not shown in FIG. 7A, in some examples, when the data trafficload on the SCell is not greater than the traffic threshold, the UE maycontinue not performing PDCCH monitoring on the SCell.

FIG. 7B is a flowchart 710 of an example method of determining anoccurrence of the monitoring-resumption event based on networksignaling. In some examples, the UE may be capable of performingcross-carrier signaling. In some such examples, the network may transmita DCI to the UE. For example, at 712, the UE may receive a DCI from afallback cell that the UE is monitoring. For example, the DCI handlingcomponent 810 may receive the DCI. In some such examples, the basestation may transmit the DCI to the UE via the fallback cell. Forexample, after the UE stops PDCCH monitoring on a first SCell, the UEmay receive DCIs for the first SCell via a fallback cell. In some suchexamples, the fallback cell may be a designated (or preconfigured) SCellfor which the UE is still performing PDCCH monitoring. In some examplesthe fallback cell may be a primary cell (PCell).

In some examples, the received DCI may be similar to the DCI used toactivate type-2 uplink configured grants and/or may be similar to theDCI used to activate type-2 downlink semi-persistent scheduling (SPS).In some examples, the received DCI may be a scheduling DCI. At 714, theUE resumes the PDCCH monitoring on the SCell in response to the receivedDCI. For example, the DCI handling component 810 may determine theoccurrence of the monitoring-resumption event and may trigger resumptionof the PDCCH monitoring on the SCell. At 716, the UE may switch from anactive BWP to a different BWP that includes a PDCCH based oninstructions in the received DCI. For example, the resume monitoringcomponent 820 switch from the active BWP to the different BWP. Forexample, the scheduling DCI may include instructions that cause the UEto switch to the different BWP.

FIG. 7C is a flowchart 720 of another example method of determining anoccurrence of the monitoring-resumption event based on networksignaling. In some examples, the UE may be configured with C-DRX. Insome such examples, at 722, the UE may receive a wakeup signalidentifying the SCell. For example, the C-DRX handling component 816 mayreceive the wakeup signal. For example, at the start of a C-DRX ONduration, the base station may transmit a wakeup signal instructing theUE which one or more SCells the UE is to perform PDCCH monitoring. At724, the UE may resume the PDCCH monitoring on the SCell in response tothe received wakeup signal. For example, the C-DRX handling component816 may determine the occurrence of the monitoring-resumption event andmay trigger resumption of the PDCCH monitoring on the SCell. Forexample, the UE may resume PDCCH monitoring on one or more SCellsidentified via the wakeup signal.

FIG. 7D is a flowchart 730 of another example method of determining anoccurrence of the monitoring-resumption event based on networksignaling. For example, at 732, the UE receives a MAC-CE from a basestation. For example, the MAC-CE handling component 814 may receive theMAC-CE. In some examples, the base station may be associated with theSCell. In some examples, the received MAC-CE may indicate to the UE oneor more SCells for which the UE is to resume PDCCH monitoring. At 734,the UE may resume the PDCCH monitoring on the SCell in response to thereceived MAC-CE. For example, the MAC-CE handling component 814 maydetermine the occurrence of the monitoring-resumption event and maytrigger resumption of the PDCCH monitoring on the SCell. For example,the UE may resume PDCCH monitoring on the one or more SCells indicatedin the MAC-CE.

FIG. 7E is a flowchart 740 of an example method of determining anoccurrence of the monitoring-resumption event based on a predefinedevent. For example, at 742, the UE may detect an occurrence of apredefined event. In some examples, the UE may be configured with C-DRX.In some such examples, at 744, the predefined event may include thestart of the C-DRX inactivity timer or may include the restart of theC-DRX inactivity timer. For example, the C-DRX handling component 816may detect the occurrence of the predefined event. At 746, the UE mayresume the PDCCH monitoring in response to the occurrence of thepredefined event. For example, the C-DRX handling component 816 triggera resumption of the PDCCH monitoring when the event is determined tohave occurred. For example, the UE may resume PDCCH monitoring on one ormore SCells at the start (or restart) of the C-DRX inactivity timer.

FIG. 7F is a flowchart 750 of another example method of determining anoccurrence of the monitoring-resumption event based on networksignaling. For example, at 752, the UE receives a scheduling DCI on asearch space of a PCell. For example, the DCI handling component 810 mayreceive the scheduling DCI. In some examples, the search space is linkedto one or more SCells. At 754, the UE may resume the PDCCH monitoring onthe SCell in response to receiving scheduling DCI. For example, the DCIhandling component 810 may determine an occurrence of themonitoring-resumption event and trigger resumption of the PDCCHmonitoring on the SCell. In some examples, the UE may resume PDCCHmonitoring on the one or more SCells linked to the search space. In someexamples, the UE may resume the PDCCH monitoring based on instructionsin the scheduling DCI.

FIG. 8 is a conceptual data flow diagram 800 illustrating the data flowbetween different means/components in an example apparatus 802. Theapparatus 802 may be a UE or a component of the UE. In the illustratedexample, the apparatus 802 includes a reception component 804, a trafficmonitoring component 806, a timer component 808, a DCI handlingcomponent 810, a MAC-CE handling component 814, a C-DRX handlingcomponent 816, a stop monitoring component 818, a resume monitoringcomponent 820, and a transmission component 822.

The reception component 804 may be configured to receive various typesof signals/messages and/or other information from other devices,including, for example, a base station 850 and/or a SCell 852. Themessages/information may be received via the reception component 804 andprovided to one or more component of the apparatus 802 for furtherprocessing and/or use in performing various operations. For example, thereception component 804 may be configured to receive PDCCH, PDSCH, awakeup signal, a MAC-CE, and/or DCI from the base station 850 and/or theSCell 852.

The traffic monitoring component 806 may be configured to determinewhether a data traffic load on the SCell satisfies a minimum trafficthreshold (e.g., as described in connection with 602 of FIG. 6A), may beconfigured to determine whether a monitoring-stopping event has occurredand stop the PDCCH monitoring on the SCell based on the data trafficload (e.g., as described in connection with 604 of FIG. 6A), may beconfigured to determine whether a data traffic load on the SCell isgreater than a traffic threshold (e.g., as described in connection with702 of FIG. 7A), and/or may be configured to stop the PDCCH monitoringon the SCell based on the determination (e.g., as described inconnection with 704 of FIG. 7A).

The timer component 808 may be configured to start or restart a timer(e.g., an SCell inactivity timer) in response to transmission ofsubsequent (or new) PUSCH and/or in response to reception of subsequent(or new) PDSCH on the SCell (e.g., as described in connection with 612of FIG. 6B) and/or may be configured to determine that amonitoring-stopping event has occurred and stop the PDCCH monitoring onthe SCell when the timer expires (e.g., as described in connection with614 of FIG. 6B).

The DCI handling component 810 may be configured to receive DCI from abase station (e.g., as described in connection with 622 of FIG. 6C), maybe configured to determine that a monitoring-stopping event has occurredand stop the PDCCH monitoring on the SCell in response to the receivedDCI (e.g., as described in connection with 624 of FIG. 6C), may beconfigured to receive DCI from a fallback cell that the apparatus ismonitoring (e.g., as described in connection with 712 of FIG. 7B), maybe configured to determine that a monitoring-resumption event hasoccurred and resume the PDCCH monitoring on the SCell in response to thereceived DCI (e.g., as described in connection with 714 of FIG. 7B), maybe configured to receive scheduling DCI on a search space of a PCell(e.g., as described in connection with 752 of FIG. 7F), and/or may beconfigured to determine that a monitoring-resumption event has occurredand resume the PDCCH monitoring on the SCell in response to the receivedscheduling DCI (e.g., as described in connection with 754 of FIG. 7F).

The MAC-CE handling component 814 may be configured to receive a MAC-CEfrom a base station (e.g., as described in connection with 632 of FIG.6D), may be configured to determine that a monitoring-resumption eventhas occurred and resume the PDCCH monitoring on the SCell in response tothe received MAC-CE (e.g., as described in connection with 634 of FIG.6D), may be configured to receive a MAC-CE from a base station (e.g., asdescribed in connection with 732 of FIG. 7D), and/or may be configuredto determine that a monitoring-resumption event has occurred and resumethe PDCCH monitoring on the SCell in response to the received MAC-CE(e.g., as described in connection with 734 of FIG. 7D).

The C-DRX handling component 816 may be configured to detect theoccurrence of a predefined event, such as the start of a C-DRX cycle(e.g., as described in connection with 642 and 644 of FIG. 6E), may beconfigured to trigger the monitoring-stoppage signaling in response tothe occurrence of a predefined event (e.g., as described in connectionwith 646 of FIG. 6E), may be configured to receive a wakeup signalidentifying one or more SCells (e.g., as described in connection with722 of FIG. 7C), may be configured to determine that amonitoring-resumption event has occurred and resume the PDCCH monitoringon the SCell in response to the received wakeup signal (e.g., asdescribed in connection with 724 of FIG. 7C), may be configured todetect the occurrence of a predefined event, such as the start of aC-DRX inactivity timer or a restart of the C-DRX inactivity timer (e.g.,as described in connection with 742 and 744 of FIG. 7E), and/or may beconfigured to determine that a monitoring-resumption event has occurredand resume the PDCCH monitoring on the SCell in response to theoccurrence of the predefined event (e.g., as described in connectionwith 746 of FIG. 7E).

The stop monitoring component 818 may be configured to stop PDCCHmonitoring on one or more SCells in response to a monitoring-stoppageevent (e.g., as described in connection with 506 of FIG. 5), may beconfigured to stop the PDCCH monitoring on the one or more SCells whilemaintaining the active BWP (e.g., as described in connection with 616 ofFIG. 6B), may be configured to stop the PDCCH monitoring on the one ormore SCells by switching from an active BWP to a different BWP that doesnot include a PDCCH (e.g., as described in connection with 618 of FIG.6B), and/or may be configured to stop the PDCCH monitoring on the one ormore SCells by switching from an active BWP to a different BWP that doesnot include a PDCCH based on instructions in received DCI (e.g., asdescribed in connection with 626 of FIG. 6C).

The resume monitoring component 820 may be configured to resume PDCCHmonitoring on one or more SCells in response to a monitoring-resumptionevent (e.g., as described in connection with 510 of FIG. 5), and/or maybe configured to resume the PDCCH monitoring on the one or more SCellsby switching from an active BWP to a different BWP that includes a PDCCHbased on instructions in received DCI (e.g., as described in connectionwith 716 of FIG. 7B).

The transmission component 822 may be configured to transmit varioustypes of signals/messages and/or other information to other devices,including, for example, the base station 850 and/or the SCell 852.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 5, 6Ato 6E, and/or 7A to 7F. As such, each block in the aforementionedflowcharts of FIGS. 5, 6A to 6E, and/or 7A to 7F may be performed by acomponent and the apparatus may include one or more of those components.The components may be one or more hardware components specificallyconfigured to carry out the stated processes/algorithm, implemented by aprocessor configured to perform the stated processes/algorithm, storedwithin a computer-readable medium for implementation by a processor, orsome combination thereof.

FIG. 9 is a diagram 900 illustrating an example of a hardwareimplementation for an apparatus 802′ employing a processing system 914.The processing system 914 may be implemented with a bus architecture,represented generally by the bus 924. The bus 924 may include any numberof interconnecting buses and bridges depending on the specificapplication of the processing system 914 and the overall designconstraints. The bus 924 links together various circuits including oneor more processors and/or hardware components, represented by theprocessor 904, the components 804, 806, 808, 810, 814, 816, 818, 820,822 and the computer-readable medium/memory 906. The bus 924 may alsolink various other circuits such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

The processing system 914 may be coupled to a transceiver 910. Thetransceiver 910 is coupled to one or more antennas 920. The transceiver910 provides a means for communicating with various other apparatus overa transmission medium. The transceiver 910 receives a signal from theone or more antennas 920, extracts information from the received signal,and provides the extracted information to the processing system 914,specifically the reception component 804. In addition, the transceiver910 receives information from the processing system 914, specificallythe transmission component 822, and based on the received information,generates a signal to be applied to the one or more antennas 920. Theprocessing system 914 includes a processor 904 coupled to acomputer-readable medium/memory 906. The processor 904 is responsiblefor general processing, including the execution of software stored onthe computer-readable medium/memory 906. The software, when executed bythe processor 904, causes the processing system 914 to perform thevarious functions described supra for any particular apparatus. Thecomputer-readable medium/memory 906 may also be used for storing datathat is manipulated by the processor 904 when executing software. Theprocessing system 914 further includes at least one of the components804, 806, 808, 810, 814, 816, 818, 820, 822. The components may besoftware components running in the processor 904, resident/stored in thecomputer readable medium/memory 906, one or more hardware componentscoupled to the processor 904, or some combination thereof. Theprocessing system 914 may be a component of the UE 350 and may includethe memory 360 and/or at least one of the TX processor 368, the RXprocessor 356, and the controller/processor 359. Alternatively, theprocessing system 914 may be the entire UE (e.g., see the UE 350 of FIG.3).

In one configuration, the apparatus 802/802′ for wireless communicationincludes means for means for monitoring a PDCCH on an SCell. Theapparatus 802/802′ may also include means for stopping the PDCCHmonitoring on the SCell in response to a monitoring-stoppage event. Theapparatus 802/802′ may also include means for resuming the PDCCHmonitoring on the SCell in response to a monitoring-resumption event,and where the SCell remains active during a period between the stoppingof the PDCCH monitoring and the resuming of the PDCCH monitoring. Theapparatus 802/802′ may also include means for determining an occurrenceof the monitoring-stoppage event upon determining that a data trafficload fails to satisfy a minimum traffic threshold. The apparatus802/802′ may also include means for starting or restarting a timer inresponse to transmission of a new PUSCH or reception of a new PDSCH onthe SCell. The apparatus 802/802′ may also include means for determiningan occurrence of the monitoring-stoppage event when the timer expires.The apparatus 802/802′ may also include means for maintaining an activeBWP on the SCell. The apparatus 802/802′ may also include means forautonomously switching to a different BWP that does not include a PDCCH.The apparatus 802/802′ may also include means for receiving DCI from abase station. The apparatus 802/802′ may also include means fordetermining an occurrence of the monitoring-stoppage signaling based onreceiving the DCI. The apparatus 802/802′ may also include means forswitching to a different BWP that does not include a PDCCH based oninstructions in the received DCI. The apparatus 802/802′ may alsoinclude means for receiving a MAC-CE from a base station, and where theMAC-CE indicates a set of SCells to stop monitoring. The apparatus802/802′ may also include means for determining an occurrence of themonitoring-stoppage event based on the received MAC-CE. The apparatus802/802′ may also include means for determining an occurrence of themonitoring-stoppage event in response to an occurrence of a predefinedevent, and where the predefined event is a start of an ON duration of aC-DRX cycle. The apparatus 802/802′ may also include means fordetermining an occurrence of the monitoring-resumption event when a datatraffic load on the SCell satisfies a traffic threshold. The apparatus802/802′ may also include means for receiving DCI from a fallback cellthat the UE is monitoring. The apparatus 802/802′ may also include meansfor determining an occurrence of the monitoring-resumption event basedon the received DCI. The apparatus 802/802′ may also include means forswitching to a different BWP that includes a PDCCH based on instructionsin the received DCI. The apparatus 802/802′ may also include means forreceiving a wakeup signal identifying the SCell. The apparatus 802/802′may also include means for determining an occurrence of themonitoring-resumption event based on receiving the wakeup signal. Theapparatus 802/802′ may also include means for receiving a MAC-CE from abase station, and where the MAC-CE indicates the UE is to resume PDCCHmonitoring on a set of SCells. The apparatus 802/802′ may also includemeans for determining an occurrence of the monitoring-resumption eventbased on the received MAC-CE. The apparatus 802/802′ may also includemeans for determining an occurrence of the monitoring-resumption eventin response to an occurrence of a predefined event, and where thepredefined event includes a start of a C-DRX inactivity timer or arestart of the C-DRX inactivity timer. The apparatus 802/802′ may alsoinclude means for receiving scheduling DCI on a search space of a PCell,and where the search space is linked to the SCell. The apparatus802/802′ may also include means for determining an occurrence of themonitoring-resumption event based on the received scheduling DCI, andwhere the UE resumes PDCCH monitoring on the SCell linked to the searchspace.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 802 and/or the processing system 914 of theapparatus 802′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 914 mayinclude the TX Processor 368, the RX Processor 356, and thecontroller/processor 359. As such, in one configuration, theaforementioned means may be the TX Processor 368, the RX Processor 356,and the controller/processor 359 configured to perform the functionsrecited by the aforementioned means.

Techniques disclosed herein facilitate monitoring PDCCH when needed(e.g., when a traffic load is high). For example, disclosed techniquesenable keeping a self-scheduling SCell active, but also enable a UE tostop monitoring PDCCH on the self-scheduling SCell when there is aperiod of inactivity in traffic. By keeping the self-scheduling SCellactive, techniques disclosed herein may enable reducing UE powerconsumption and may also enable avoiding latency incurred byre-activating the SCell. Thus, techniques disclosed herein provide alow-latency technique for a UE to stop and restart monitoring PDCCH on aself-scheduling SCell.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication at a userequipment (UE), comprising: monitoring a physical downlink controlchannel (PDCCH) on a secondary cell (SCell), the UE configured forcommunication on a primary cell (PCell) and the SCell; receivingdownlink control information (DCI); stopping PDCCH monitoring on theSCell in response to a monitoring-stoppage event, themonitoring-stoppage event comprising reception of the DCI; switching toa different bandwidth part (BWP) that does not include the PDCCH basedon instructions in the DCI; and resuming the PDCCH monitoring on theSCell in response to a monitoring-resumption event, the SCell remainingactive during a period between stopping the PDCCH monitoring andresuming the PDCCH monitoring.
 2. The method of claim 1, wherein the DCIis received from a base station.
 3. The method of claim 1, wherein theDCI is received from a fallback cell that the UE is monitoring while thePDCCH monitoring on the SCell is stopped, wherein themonitoring-resumption event comprises reception of the DCI from thefallback cell, the fallback cell being a cell different than the SCell.4. The method of claim 3, wherein the fallback cell is a designatedSCell.
 5. The method of claim 3, wherein the fallback cell is the PCell.6. The method of claim 1, wherein the monitoring-resumption eventcomprises a data traffic load on the SCell satisfying a trafficthreshold.
 7. The method of claim 1, wherein the UE is configured withconnected mode discontinuous reception (C-DRX) and is configured tomonitor a set of SCells, wherein the monitoring-stoppage event is basedon a start of an ON duration of a C-DRX cycle, wherein stopping thePDCCH monitoring includes stopping the PDCCH monitoring on a subset ofSCells of the set of SCells, the subset of SCells including one or moreSCells of the set of SCells and including at least the SCell.
 8. Themethod of claim 1, wherein the UE is configured with connected modediscontinuous reception (C-DRX) and the UE is configured to monitor aset of SCells, and the method further comprises: receiving a wakeupsignal identifying a subset of SCells of the set of SCells, wherein themonitoring-resumption event is based on receiving the wakeup signal, andwherein resuming the PDCCH monitoring includes resuming the PDCCHmonitoring on the subset of SCells, the subset of SCells including oneor more SCells of the set of SCells.
 9. The method of claim 1, whereinthe UE is configured with connected mode discontinuous reception (C-DRX)and the UE is configured to monitor a set of SCells, wherein themonitoring-resumption event is based on a start of a C-DRX inactivitytimer or a restart of the C-DRX inactivity timer, wherein resuming thePDCCH monitoring includes resuming the PDCCH monitoring on a subset ofSCells of the set of SCells, the subset of SCells including one or moreSCells of the set of SCells and including at least the SCell.
 10. Amethod of wireless communication at a user equipment (UE), comprising:monitoring a physical downlink control channel (PDCCH) on a secondarycell (SCell), the UE configured for communication on a primary cell(PCell) and the SCell; stopping PDCCH monitoring on the SCell inresponse to a monitoring-stoppage event; receiving scheduling downlinkcontrol information (DCI) in a search space on the PCell, the SCellbeing linked to the search space, the scheduling DCI being fortransmission of a new physical uplink shared channel (PUSCH) or forreception of a new physical downlink shared channel (PDSCH) in thesearch space on the PCell; and resuming the PDCCH monitoring on theSCell in response to a monitoring-resumption event, the SCell remainingactive during a period between stopping the PDCCH monitoring andresuming the PDCCH monitoring, the UE resuming the PDCCH monitoring onthe SCell linked to the search space in response to receiving thescheduling DCI in the search space on the PCell.
 11. The method of claim10, wherein the monitoring-stoppage event comprises determining that adata traffic load fails to satisfy a minimum traffic threshold.
 12. Amethod of wireless communication at a user equipment (UE), comprising:monitoring a physical downlink control channel (PDCCH) on a secondarycell (SCell), the UE configured for communication on a primary cell(PCell) and the SCell; starting or restarting a timer in response totransmission of a new physical uplink shared channel (PUSCH) orreception of a new physical downlink shared channel (PDSCH) on theSCell; stopping PDCCH monitoring on the SCell in response to amonitoring-stoppage event, the monitoring-stoppage event comprising anexpiration of the timer; and resuming the PDCCH monitoring on the SCellin response to a monitoring-resumption event, the SCell remaining activeduring a period between stopping the PDCCH monitoring and resuming thePDCCH monitoring.
 13. The method of claim 12, wherein stopping the PDCCHmonitoring includes autonomously switching to a different bandwidth part(BWP) that does not include the PDCCH if the timer expires.
 14. Anapparatus for wireless communication at a user equipment (UE),comprising: means for monitoring a physical downlink control channel(PDCCH) on a secondary cell (SCell), the UE configured for communicationon a primary cell (PCell) and the SCell; means for receiving downlinkcontrol information (DCI); means for stopping PDCCH monitoring on theSCell in response to monitoring-stoppage event, the monitoring-stoppageevent comprising reception of the DCI; means for switching to adifferent bandwidth part (BWP) that does not include the PDCCH based oninstructions in the DCI; and means for resuming the PDCCH monitoring onthe SCell in response to a monitoring-resumption event, the SCellremaining active during a period between stopping the PDCCH monitoringand resuming the PDCCH monitoring.
 15. The apparatus of claim 14,further comprising: means for receiving the DCI from a base station. 16.The apparatus of claim 14, further comprising: means for receiving theDCI from a fallback cell that the UE is monitoring while the PDCCHmonitoring on the SCell is stopped, wherein the monitoring-resumptionevent comprises reception of the DCI from the fallback cell, thefallback cell being a cell different than the SCell.
 17. The apparatusof claim 14, wherein the monitoring-resumption event comprises a datatraffic load of the SCell satisfying a traffic threshold.
 18. Anapparatus for wireless communication at a user equipment (UE),comprising: means for monitoring a physical downlink control channel(PDCCH) on a secondary cell (SCell), the UE configured for communicationon a primary cell (PCell) and the SCell; means for stopping PDCCHmonitoring on the SCell in response to monitoring-stoppage event: meansfor receiving scheduling downlink control information (DCI) in a searchspace on the PCell, the SCell being linked to the search space, thescheduling DCI being for transmission of a new physical uplink sharedchannel (PUSCH) or for reception of a new physical downlink sharedchannel (PDSCH) in the search space on the PCell; and means for resumingthe PDCCH monitoring on the SCell in response to a monitoring-resumptionevent, the SCell remaining active during a period between stopping thePDCCH monitoring and resuming the PDCCH monitoring, the UE resuming thePDCCH monitoring on the SCell linked to the search space in response toreceiving the scheduling DCI in the search space on the PCell.
 19. Theapparatus of claim 18, wherein the monitoring-stoppage event comprisesdetermining that a data traffic load fails to satisfy a minimum trafficthreshold.
 20. An apparatus for wireless communication at a userequipment (UE), comprising: means for monitoring a physical downlinkcontrol channel (PDCCH) on a secondary cell (SCell), the UE configuredfor communication on a primary cell (PCell) and the SCell; means forstarting or restarting a timer in response to a transmission of a newphysical uplink shared channel (PUSCH) or reception of a new physicaldownlink shared channel (PDSCH) on the SCell, means for stopping PDCCHmonitoring on the SCell in response to monitoring-stoppage event, themonitoring-stoppage event comprising an expiration of the timer; andmeans for resuming the PDCCH monitoring on the SCell in response to amonitoring-resumption event, the SCell remaining active during a periodbetween stopping the PDCCH monitoring and resuming the PDCCH monitoring.21. An apparatus for wireless communication at a user equipment (UE),comprising: a memory; and at least one processor coupled to the memoryand configured to: monitor a physical downlink control channel (PDCCH)on a secondary cell (SCell), the UE configured for communication on aprimary cell (PCell) and the SCell; receive downlink control information(DCI); stop PDCCH monitoring on the SCell in response tomonitoring-stoppage event, the monitoring-stoppage event comprisingreception of the DCI; switch to a different bandwidth part (BWP) thatdoes not include the PDCCH based on instructions in the DCI; and resumethe PDCCH monitoring on the SCell in response to a monitoring-resumptionevent, the SCell remaining active during a period between stopping thePDCCH monitoring and resuming the PDCCH monitoring.
 22. The apparatus ofclaim 21, wherein the at least one processor is further configured to:receive the DCI from a base station.
 23. The apparatus of claim 21,wherein the at least one processor is further configured to: receive theDCI from a fallback cell that the UE is monitoring while the PDCCHmonitoring on the SCell is stopped, wherein the monitoring-resumptionevent comprises reception of the DCI from the fallback cell, thefallback cell being a cell different than the SCell.
 24. An apparatusfor wireless communication at a user equipment (UE), comprising: amemory; and at least one processor coupled to the memory and configuredto: monitor a physical downlink control channel (PDCCH) on a secondarycell (SCell), the UE configured for communication on a primary cell(PCell) and the SCell; stop PDCCH monitoring on the SCell in response tomonitoring-stoppage event; receive scheduling downlink controlinformation (DCI) in a search space on the PCell, the SCell being linkedto the search space, the scheduling DCI being for transmission of a newphysical uplink shared channel (PUSCH) or for reception of a newphysical downlink shared channel (PDSCH) in the search space on thePCell; and resume the PDCCH monitoring on the SCell in response to amonitoring-resumption event, wherein the SCell remains active during aperiod between stopping the PDCCH monitoring and resuming the PDCCHmonitoring, the UE resuming the PDCCH monitoring on the SCell linked tothe search space in response to receiving the scheduling DCI in thesearch space on the PCell.
 25. A non-transitory computer-readable mediumstoring computer executable code for wireless communication at a userequipment (UE), the computer executable code, when executed, to cause aprocessor to: monitor a physical downlink control channel (PDCCH) on asecondary cell (SCell), the UE configured for communication on a primarycell (PCell) and the SCell; receive downlink control information (DCI);stop PDCCH monitoring on the SCell in response to monitoring-stoppageevent, the monitoring-stoppage event comprising reception of the DCI;switch to a different bandwidth part (BWP) that does not include thePDCCH based on instructions in the DCI; and resume the PDCCH monitoringon the SCell in response to a monitoring-resumption event, the SCellremaining active during a period between stopping the PDCCH monitoringand resuming the PDCCH monitoring.